Lead/chloride/alumina isomerization catalyst for gasoline

ABSTRACT

A heavy gasoline fraction having a relatively low research octane number as for instance a fraction obtained from a cat cracker gasoline is passed over a chlorided alumina catalyst modified by the addition of 0.01 to 5 weight per cent lead calculated as PbO. The presence of lead decreases the cracking activity of the catalyst so that it can be operated at a higher temperature which favors increased formation of aromatic hydrocarbons.

United States Patent 1191 1111 3,929,623

Nelson 1 Dec. 30, 1975 LEAD/CHLORIDE/ALUMINA 3,227,658 1/1966 Myers et al. 252 443 [SOMERIZATION CATALYST FOR 3,666,412 5/1972 Sowards 423/162 GASOLINE 3,692,863 9 1973 Kmecak 260 6833 3,711,425 1 1973 Suggitt et al 252 439 William T. Nelson, Bartlesville, Okla.

Phillips Petroleum Company, Bartlesville, Okla.

Filed: Nov. 25, 1974 Appl. No.: 526,940

lnventor:

Assignee:

US. Cl. 208/135; 208/139; 252/441 Int. Cl. C10G 35/06; B01J 27/06 Field of Search 208/135, 139; 252/441 References Cited UNITED STATES PATENTS l/l960 Myers et al. 260/680.68 4/1961 Hervert et al 252/441 Primary Examiner-Delbert E. Gantz Assistant ExaminerJuanita M, Nelson [57] ABSTRACT A heavy gasoline fraction having a relatively low research octane number as for instance a fraction obtained from a cat cracker gasoline is passed over a chlorided alumina catalyst modified by the addition of 0.01 to 5 Weight per cent lead calculated as PbO. The presence of lead decreases the cracking activity of the catalyst so that it can be operated at a higher temperature which favors increased formation of aromatic hydrocarbons.

8 Claims, N0 Drawings LEAD/CHLORIDE/ALUMINA ISOMERIZATION CATALYST FOR GASOLINE BACKGROUND OF THE INVENTION This invention relates to a hydrocarbon reforming process utilizing a-lead/chloride/alumina catalyst.

It has long been known to use an alumina base containing platinum and a halogen for the reforming of gasoline fractions such as the higher boiling part of the straight run gasoline contained naturally in crude oil and the heavy gasoline fraction boiling between about 180 to 400 F in a full range gasoline produced by catcracking. These materials inherently have a research octane number (RON) clear of less than about 90 and must be reformed to produce a product having a higher RON by increasing the aromatic content of the reformate. One of the factors which has limited the use of catalytic reforming has been the excessive formation of light gases such as methane, ethane, propane, ethylene, propylene and butenes. Thus there is a need for an inexpensive catalyst system which is effective in producing large amounts of aromatics so as to raise the RON without significant formation of light gases. Hydrogenation-dehydrogenation catalysts, for example, are undesirable since in the presence of hydrogen they would cause hydrogenation of the olefins contained in the gasoline to paraffins thus resulting in the production of gasoline having lowered RON values rather than higher values.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved catalyst for reforming relatively low octane gasoline fractions;

it is a further object of this invention to provide an improved isomerization process to produce relatively high octane gasoline;

it is yet a further object of this invention to provide an inexpensive catalyst which is effective in producing high octane products; and

it is still yet a further object of this invention to avoid the production of large amounts of light gases.

In accordance with this invention a relatively low octane gasoline fraction is passed over a catalyst consisting essentially of a chlorided alumina base modified by the addition of 0.01 to 5 weight per cent lead calculated as PbO based on the weight of said catalyst.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The base for use in the catalysts of this invention can be any active alumina of the type known in the art. The preferred material is gamma-alumina having a specific surface area of from 100 to 500 square meters per gram, a specific pore volume of about 0.1 to 1 cc per gram, and an apparent bulk density of about 0.6 to I The alumina must be chlorided preferably by treating with aqueous solutions of HCl so as to give chlorine in an amount within the range of 0.1 to 5 weight per cent calculated as hydrogen chloride based on the weight of the catalyst. Gaseous I-lCl or ammonium chloride can also be used.

The third component of the catalyst system is lead which is present in an amount within the range of 0.01 to 5 weight per cent of lead calculated as PbO based on the weight of catalyst. The lead can be added to the chlorided support, for example, in the form of any convenient salt which is thereafter converted to PbO by heating in air, for example. Water soluble salts of lead in the plus two valence state such as lead nitrate and lead acetate are preferred.

The catalyst of this invention represents a different class of catalysts from the platinum-containing catalysts of the prior art. In addition with this distinct new class of catalyst of this invention, it is essential that the halogen be a chloride. Accordingly, the catalyst is described as consisting essentially of the alumina base, the chloride, and the lead so as to define this distinction from the prior art catalyst systems containing a platinum group metal either alone or with a fluoride.

The hydrocarbons used in the process of this invention comprise olefins, paraffins and naphthenes which are usually present in thermally and catalytically cracked gasolines. The gasolines are substantially olefinic in nature and generally contain at least 25 volume per cent olefin and frequently contain 40 per cent or more olefins. The gasoline can be a full boiling range material having an initial ASTM boiling range between about 60F and about F and an end point between about 250F and about 450F or it can be a narrow fraction selected from within this boiling range. It is presently preferred to use such a narrow fraction within this range which has an initial boiling point between about l60F and about 200F with an end point between about 375F and about 425F.

The catalyst can be calcined prior to use by heating in air at 600 to l200F, preferably 850l 000F for 0.1 to 50 preferably 1 to 5 hours or an oxygen-containing gas such as air can be passed over the catalyst while it is in the reactor as the reactor is being brought up to temperature thus eliminating the necessity for a separate calcination step.

The operating conditions used in the process of this invention are varied but are such that the octane rating of the gasoline is substantially improved. Temperatures between about 600F and about 1200F, more preferably about 800F to about 1 100F, most preferably 900 to l050F are employed. Within these temperature ranges, liquid hourly space velocities ranging from about 0.1 to about 20, more preferably from about 1 to about 6 are used. Pressures in the isomerization zone range from about 0 to 100 psig. lf hydrogen is used the hydrocarbon-hydrogen mole ratio will range from about 0.25 to 10.

Maintenance of catalyst activity during use in this process can be aided, if desired, by including 0.00l to about 1 weight per cent chloride in the feed in the form of chlorinated hydrocarbons such as carbon tetrachloride, chloroform, ethyl chloride, etc.

EXAMPLE 1 The chlorided alumina catalyst used as the control was prepared by crushing a commercially obtained gamma-alumina in the form of 56-inch extrudate and screening the material to obtain lO-20 mesh particles. The particles were dried at 215F for 7 hours in an air oven and to 63.8 g of the cooled dried product was added 31.9 g of 2 weight per cent hydrochloric acid solution. The liquid was just taken up by the solid. The resulting mixture was dried for 4 hours at 210-240F and then allowed to cool overnight at room temperature in a vacuum desiccator. The calculated amount of chloride impregnated on the catalyst was 0.96 weight per cent calculated as HCl and based on the total weight of the catalyst.

The lead-promoted catalyst of this invention was prepared by impregnating 19.1 grams of the chlorided alumina with 0.600 grams of Pb(C l-l O .3I-1 O dissolved in 10 cc of water. The resulting mixture was dried at 215F for 3 hours. The amount of lead, calculated as PbO, impregnated on the catalyst was 1.94 weight per cent based on the total weight of the catalyst.

Each of the catalysts (about 1415 grams) was individually charged to a reactor at room temperature and the reactor was brought up to operating temperature while nitrogen was passed through the apparatus in the control runs and nitrogen plus 1 volume per cent oxygen in the invention runs to convert any remaining lead acetate to lead monoxide.

The feed for the runs used in the process of this invention was obtained by fractionating a caustic-washed but not inhibited Kansas City cat cracked full range gasoline to obtain a heavy fraction with a boiling point range from 167F to 407F. The full range gasoline had an API gravity of 59.0, a research octane number (RON) clear of 92.3 and a motor octane number (MON) clear of 80.5. The olefin content was approximately 50 LV per cent. The heavy fraction obtained had an API gravity of 49.1, RON (clear) of 89.2, a MON (clear) of 79.3 and it consisted of about 63 liquid volume per cent of the starting material. The light un used fraction had an API gravity of 80.3, RON (clear) of 95.3 and MON (clear) of 81.6.

The heavy gasoline fraction was isomerized at several temperatures to illustrate the utility of the lead-promoted catalyst in comparison with the unleaded control catalyst. Analyses of products was made using gas-liquid chromatography. The operating conditions employed and the results obtained are presented in Table 1.

5 vention. It is clearly seen at tem eratures as much as 200F higher than the best resJ-Eji obtained with the control catalyst operating at 800F that the invention catalyst is suppressing the formation of cracked gases, thus the yields of the desired product remain higher than those obtained with the control catalyst. Moreover, the RON values of the products, even at 250"]? above the best operating temperature of the control catalyst, are higher than the control values. The relative rating values are also significantly higher than the control up to 1000F reactor temperature and about equal at 1050F compared to the best control operating at 800F. I

In a subsequent operation, the fraction upgraded by isomerization is blended with the light fraction to obtain a full range gasoline with a higher RON (clear) rating compared to the untreated gasoline. 7

While this invention has been described in detail for the purpose of illustration, it is not to be construed as limited thereby but is intended to cover all changes and modifications within the spirit and scope thereof.

1 claim:

1. A process for reforming a gasoline comprising passing said gasoline into contact with a catalyst consisting essentially of 1. an alumina base;

2. chlorine in an amount within the range of 0.1 to 5 weight per cent calculated as hydrogen chloride based on the weight of said catalyst; and

3. 0.01 to 5 weight per cent lead calculated as PbO based on the weight of said catalyst at a temperature within the range of 600 to 1200F;

and recovering a product having a higher octane rating.

2. A process according to claim 1 wherein said baseis gamma-alumina.

3. A method according to claim 1 wherein said chlorine is imparted by contacting said alumina with a hydrochloric acid solution.

4. A method according to claim 1 wherein said lead is introduced by impregnating said-base with a solution of a lead compound and thereafter contacting said thus impregnated base with air at an elevated temperature Table l Catalyst Chlorided Alumina Lead Oxide/chlorided alumina Run No l 2 3 4 5 Reactor Temp. F 800 850 900 950 1000 1050 Run Length, Hrs. 4 4 5 5 5 5 Space Rate (vol/vol/hr) 2.93 2.95 3.05 3.01 3.03 3.04 Yields. Wt.

Gas 4.39 5.28 2.08 3.37 3.80 5.99 C,+ liquid 95.3 94.4 97.6 96.3 95.8 93.8 Coke 0.28 0.30 0.33 0.34 0.43 0.16 Octane Ratings of C liquid RON (clear) 92.0 91.4 92.6 92.3 92.4 93.2 MON (clear) 81.4 80.9 80.6 80.0 80.6 80.7 Octane No. (RON) X Wt. Fraction 87.7 86.3 90.4 88.9 88.5 87.4 Yield to oxidize the lead compound to said PbO.

5. A method according to claim 1 wherein said temperature is within the range of 800 to 1100F.

6. A method according to claim 1 wherein said temperature is within the range of 900 to 1050F.

Inspection of the results shows that with a chlorided alumina catalyst, production of cracked material becomes objectionably high at a reactor temperature of about 850 the yield of liquid product is decreasing, the RON (clear) value is decreasing and a relative rating 6 contacting said alumina with a hydrochloric acid solution, said temperature is within the range of 900 to 1050F and said gasoline is cat cracked gasoline having a research octane number of no more than 90. 

1. A PROCESS FOR REFORMING A GASOLINE COMPRISING PASSING SAID GASOLINE INTO CONTACT WITH CATALYST CONSISTING ESSENTIALLY OF
 1. AN ALUMINA BASE;
 2. CHLORINE IN AN AMOUNT WITHIN THE RANGE OF 0.1 TO 5 WEIGHT PER CENT CALCULATED AS HYDROGEN CHLORIDE BASED ON THE WEIGHT OF SAID CATALYST; AND
 3. 0.01 TO 5 WEIGHT PER CENT LEAD CALCULATED AS PBO BASED ON THE WEIGHT OF SAID CATALYST AT A TEMPERATURE WITHIN THE RANGE OF 600* TO 1200*F; AND RECOVERING A PRODUCT HAVING A HIGHER OCTANE RATING.
 2. chlorine in an amount within the range of 0.1 to 5 weight per cent calculated as hydrogen chloride based on the weight of said catalyst; and
 2. A process according to claim 1 wherein said base is gamma-alumina.
 3. A method according to claim 1 wherein said chlorine is imparted by contacting said alumina with a hydrochloric acid solution.
 3. 0.01 to 5 weight per cent lead calculated as PbO based on the weight of said catalyst at a temperature within the range of 600* to 1200*F; and recovering a product having a higher octane rating.
 4. A method according to claim 1 wherein said lead is introduced by impregnating said base with a solution of a lead compound and thereafter contacting said thus impregnated base with air at an elevated temperature to oxidize the lead compound to said PbO.
 5. A method according to claim 1 wherein said temperature is within the range of 800* to 1100*F.
 6. A method according to claim 1 wherein said temperature is within the range of 900* to 1050*F.
 7. A method according to claim 1 wherein said gasoline is relatively low octane gasoline from a cracking operation.
 8. A method according to claim 7 wherein said alumina is gamma-alumina, said chlorine is imparted by contacting said alumina with a hydrochloric acid solution, said temperature is within the range of 900* to 1050*F and said gasoline is cat cracked gasoline having a research octane number of no more than
 90. 